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United States Patent | 5,244,450 |
Koehn | September 14, 1993 |
To make blocks of bags having blocked stubs, which are joined by perforation lines substantially only to the lower opening-defining edge of each block, which lower edge is separated by a substantially continuous slit from the upper opening-defining edge, a tubular web of synthetic thermoplastic material is formed in partial regions with perforation lines extending through both plies. Only the upper ply is cut to form separating slits extending substantially throughout the width of that upper ply. The bags are then separated from the tubular web by hot-wire welding and are stacked. To make blocks of bags in which each bag is joined only at its rear wall to the stub, which serves to stack and retain the bag, transverse perforation lines consisting of holes or slits are formed in the upper ply at the opening-defining edges of the bags to be formed, and both plies are subsequently formed with transverse perforation slits, which are so offset that over the width of the initially formed perforation holes the upper ply is entirely separated from the stub and the lower ply is joined to the stub by lands adjacent to the initially formed overlying perforation line.
Inventors: | Koehn; Uwe (Osnabruck, DE) |
Assignee: | Windmoller & Holscher (Lengerich, DE) |
Appl. No.: | 902726 |
Filed: | June 23, 1992 |
Jun 24, 1991[DE] | 4120802 | |
Jul 22, 1991[DE] | 4124288 |
Current U.S. Class: | 493/195; 493/196; 493/200; 493/201; 493/238; 493/267; 493/363 |
Intern'l Class: | B31B 001/14 |
Field of Search: | 493/194,195,196,197,198,203,200,201,238,239,267,362,363 |
3372625 | Mar., 1968 | Simecek | 493/194. |
3893382 | Jul., 1975 | Bosse | 493/194. |
4285681 | Aug., 1981 | Walitalo | 493/194. |
4785696 | Nov., 1988 | Martiny | 493/362. |
4983155 | Jan., 1991 | Stobb | 493/361. |